Ok I just costed out on ocuk a
Quad core cpu
Asus mobo
2 gig ram
500 gig hdd
Dual layer dvd rw
basic case
Gigabyte 460 watt psu
8600 GT gfx
OEM Home premium
All for less than £450 quid delivered. And OCUK is not the cheapest place to shop.
No I am sure you could find someone local to knock it up? I often do just builds for not a huge fee as I am not greedy I just enjoy doing it. This should give you an idea of what you can get for the top end of your budget
Having a gfx even if not gaming removes a possible bottleneck. You could save 25/30 quid on an even cheaper one (which woudl come close to getting someone like me to build it
)
If you went AMD dual core you can knock 50-70 quid at least off the price.
BTW can be built with XP instead